Fuel compositions



3,019,094 FUEL COMPOSITIONS Joseph Ray Bondreaux, Lake Jackson, and FredStephenson McDonald, Freeport, Tex., assignors to The Dow ChemicalCompany, Midland, Mich, a corporation of Delaware No Drawing. Filed Feb.14, 1957, Ser. No. 640,074

7 Claims. (CI. 44-56) This invention relates to a fuel composition forsparkignition internal combustion engines, and more particularly, to afuel composition containing an additive to improve the performancecharacteristics of the fuel and a method for decreasing the octanerequirement increase in an engine.

In recent years the manufacturers of automotive engines have steadilyincreased the compression ratios of the engines to increase thehorsepower. This trend presents a serious problem to the petroleumindustry in that the steady increase in compression ratios necessitatesthe production of a gasoline with higher octane rating for satisfactoryanti-knock performance. To meet the demands of the high compressionengines etforts have been directed primarily to the development of motorfuels with higher octane values. This has been largely accomplished bysubjecting the gasoline type fuels to severe alkylation and by theaddition of additives such as tetraethyl lead to raise the octane valueof the fuel. It is known that in the operation of an internal combustionengine deposits are formed in the combustion chamber of the engine andthat the engine which has been used requires a fuel of higher octanerating than a new or clean engine in order not to knock. As a new orclean engine is used, the octane requirement of the engine increaseswith conitnued use until a point is reached where further use will notincrease the octane requirement. Apparently, the deposits do notincrease above a certain point or, if they do, the additional depositsdo not atfect the octane requirement characteristics of the engine. Whenthis leveling off point is reached, the used or dirty engine may have anoctane requirement of 10 or more numbers higher than a new or cleanengine. Thus, a fuel additive which would improve the performancecharacteristics of the fuel by reducim the octane requirement increaseof an engine in which it is used, would enable the manufacturer of afuel of lower octane number to meet the re quirements of the highcompression engines.

It is, therefore, a principal object of this invention to provide a fuelcomposition containing an additive which would have improved performancecharacteristics by reducing the octane requirement increase. A furtherobject is to provide a method of reducing the octane re quirementincrease of an engine which occurs with the use of the engine.

The above and other objects are accomplished by aciding a small amountof 1,Z-dimethoxy-l-phenylethane to gasoline. Thus, the-re is prepared anew fuel composition which will produce a much smaller octanerequirement increase when the engine is operated on this fuel. Theaddition of a small amount of 1,2-dimethoxy-1-phenylethane does notmaterially raise the octane rating of the fuel, but when the fuel isused in the engine, it decreases the tendency of the engine to knock dueto the increase of octane requirement. =Further pre-ignition andautoignition are substantially reduced. With a fuel containing theadditive, the increase in octane requirements is around 4 to 5 octanenumbers as compared to 9 or 10 numbers increase without the additive.Since most of the fuel is consumed by engines which have been used andwould be considered dirty, the octane rating of the fuel marketed musthave sufiicient octane rating for antiknock performance in theseengines. Thus by using this additive, a fuel having an octane rating ofaround 5 octane numbers lower can be marketed and will give the requiredperformance.

The term octane requirement, as used herein, means the minimum octanevalue of the fuel which will give knock-free performance in the engineand the term octane requirement increase means the increase in theoctane requirement of an engine which occurs when a new or clean engineis used and deposits are formed in the combustion chamber thus requiringa fuel of higher octane number to give knock-free performance.

The gasoline in the composition may or may not contain other additives.Gasolines used today for spark ignition internal combustion enginescommonly contain a lead alkyl anti-knock compound, such as tetraethyllead, as an additive to raise the octane rating of the fuel. Gasolinesmay also contain additional additives, such as volatile alkyl halideswhich are added to reduce the deposition of the combustion products ofthe anti-knock componds added, anti-oxidants, a dye, and otheradditives. While the addition of 1,2-dimethoxy-l-phenylethane ingasolines which may or may not contain other additives is effective inreducing the octane requirement increase of these fuels, it isespecially effective in leaded gasolines. The octane requirementincrease is much greater when an engine is operated with leaded gasolineor gasoline containing tetraethyl lead than with unleaded gasolines.Thus the improvement obtained is much greater when the additive is usedin this gasoline.

Only a small amount of 1,2-dirnethoxy-1-phenylethane is necessary toeffectively reduce the octane requirement increase of an engine. Thelower limit of the additive used is generally around 1 milliliter pergallon of fuel, although smaller amounts may be used to obtainsignificant improvement in lowering the octane requirement increase.Amounts up to 20 milliliters per gallon may be used, but it is preferredto use from 2 to 8 milliliters per gallon. Concentrations over 20milliliters per gallon, while not deleterious, are uneconomical. Theadditive is soluble in the gasoline and the new fuel composition canthus be easily prepared by mixing the desired amount of the additive inthe gasoline.

In the examples below, 1955 Oldsmobile production models, 8 cylinder,V-8 internal combustion engines were employed. These engines had an 8.5to 1 compression ratio with 324.3 cubic inch displacement, a maximumhorsepower of 202 at 4000 rpm, and a torque rating of 332 pounds perfoot at 2400 rpm. The spark advance was l0.5 at 1200 r.p.m. and 22 at2200 rpm. Prior to each test, the engines were completely dismantled andthoroughly cleaned and all parts critically inspected. All parts thatdid not meet the measurements, tolerances, clearances, etc. specified bythe Oldsmobile Service Manual were replaced. Each run was begun with anew set of spark plugs. The octane requirement for each of the engineswas determined before the test and the data obtained in the runs werecorrected to a base octane requirement of 80.

The control fuel was octane premium gasoline. This gasoline had anA.P.I. gravity of 59.45, a boiling range of 97 to 415 F., and containedfrom 2 to 2.4 millimeters of tetraethyl lead per gallon. The test fuelconsisted of the control fuel to which was added1,2-dimethoxy-l-phenylethane as an additive.

Example I Four 100 hour test runs were made where two engines wereoperated on the control fuel and two engines were operated on the newfuel composition containing the additive.

During the test the octane requirements of the engines were determinedafter each 20 hours of operation. At

intervals of 20 hours the engines were shut down, the spark plugscarefully removed so as not to disturb any deposits, and a special setof spark plugs, reserved for rating during the particular run, wereinstalled. Primary reference fuels consisting of mixtures of n-heptaneand iso-octane of varied octane number were supplied to the carburetor.The lowest octane number employed that did not produce audible knock wastaken as a minimum octane requirement. Humidity and barometric pressuredifferences were corrected according to the standard methods. For every30 grains of water above the standard humidity of 60 grains per pound ofdry air, a correction of one octane number was added to the observedvalue. The ratio of the barometric pressure to octane requirement isinversed so that for every increase of pressure of 0.3 inch of mercuryabove the standard barometric pressure of 29.92 inches of mercury, acorrection of one octane number was subtracted. After the octanerequirement of the engine was determined, the rating plugs were removedand discarded. The original spark plugs were replaced and the enginesagain operated.

The four runs were made using an SAE W-30 multigrade petroleum base oilcontaining a polymethacrylate viscosity index improving compound in theengines.

The maximum octane requirement increase obtained in the 100 hour testswith the control fuel was 8.19 for one of the engines and 9.05 for theother. The engines operating on the fuel composition containing 6milliliters of 1,2-dirnethoxy-1-phenylethane per gallon had an octanerequirement increase of 4.11 and 4.79, respectively. Thus, by using theadditive in the fuel the octane requirement increase for the engines wasreduced by around four octane numbers.

Example 11 Three runs using a fuel containing the new additive and twocontrol runs were performed in the same manner as that described inExample I. In these runs, however, a commercially available SAE 30 motoroil containing detergent, antioxidant, and alkaline reserve additiveswas used in the engines.

The maximum octane requirement increase obtained in the one hundred hourtests with the control fuel was 8.46 for one of the engines and 10.06for the other. For

two of the experimental runs, 6 milliliters of1,2-dimethoxy-l-phenylethane were added per gallon of gasoline. In thesetwo runs, an octane requirement increase of 4.78 and 5.04 were obtained.In the third experimental run, 10 milliliters of the additive per gallonof gasoline were used, and an octane requirement increase of 5.34 octanenumbers was realized.

What is claimed is:

1. A fuel composition for spark ignition internal cornbustion engines,which consists substantially of gasoline and a small amount of1,2-dimethoxy-1-phenylethane sufficient to decrease the octanerequirement increase of the fuel.

2. A fuel composition for spark ignition internal combustion engines,which consists substantially of gasoline and from 1 to 20 milliliters of1,2-dimethoxy-1-phenylethane per gallon.

3. A fuel composition for spark ignition internal combustion engines,which consists substantially of gasoline and from 2 to 8 milliliters ofl,2-dimethoxy-1-phenylethane per gallon.

4. The fuel composition of claim 3 wherein the gasoline is leadedgasoline.

5. In the operation of a sprak ignition internal combustion engine, thestep to decrease the octane requirement increase, which comprisesburning gasoline in the engine to which is added a small amount of1,2-dimethoxy-l-phenylethane sufficient to decrease the octanerequirement increase of the gasoline.

6. In the operation of a spark ignition internal combustion engine, thestep to decrease the octane requirement increase, which comprisesburning gasoline in the engine to which is added1,Z-dimethoxy-l-phenylethane in proportions of from 1 to 20 millilitersof 1,2,-dimethoxy-l-phenylethane per gallon.

7. The process according to claim 6, wherein the 1,2-dimethoxy-l-phenylethane is added in proportions of 2 to 8 millilitersper gallon.

References Cited in the file of this patent UNITED STATES PATENTS1,582,420 Nikaido Apr. 27, 1926 2,143,870 Ellis Jan. 17, 1939 2,768,212Copenhaver Oct. 23, 1956 2,878,109 Wood et al. Mar. 17, 1959

1. A FUEL COMPOSITION FOR SPARK IGNITION INTERNAL COMBUSTION ENGINES,WHICH CONSISTS SUBSTANTIALLY OF GASOLINE AND A SMALL AMOUNT OF1,2-DIMETHOXY-1-PHENYLETHANE SUFFICIENT TO DECREASE THE OCTANEREQUIREMENT INCREASE OF THE FUEL.